From: Michael Chan Date: Fri, 4 May 2018 00:04:27 +0000 (-0400) Subject: tg3: Fix vunmap() BUG_ON() triggered from tg3_free_consistent(). X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=d89a2adb8bfe6f8949ff389acdb9fa298b6e8e12;p=openwrt%2Fstaging%2Fblogic.git tg3: Fix vunmap() BUG_ON() triggered from tg3_free_consistent(). tg3_free_consistent() calls dma_free_coherent() to free tp->hw_stats under spinlock and can trigger BUG_ON() in vunmap() because vunmap() may sleep. Fix it by removing the spinlock and relying on the TG3_FLAG_INIT_COMPLETE flag to prevent race conditions between tg3_get_stats64() and tg3_free_consistent(). TG3_FLAG_INIT_COMPLETE is always cleared under tp->lock before tg3_free_consistent() and therefore tg3_get_stats64() can safely access tp->hw_stats under tp->lock if TG3_FLAG_INIT_COMPLETE is set. Fixes: f5992b72ebe0 ("tg3: Fix race condition in tg3_get_stats64().") Reported-by: Zumeng Chen Signed-off-by: Michael Chan Signed-off-by: David S. Miller --- diff --git a/drivers/net/ethernet/broadcom/tg3.c b/drivers/net/ethernet/broadcom/tg3.c index 08bbb639be1a..9f59b1270a7c 100644 --- a/drivers/net/ethernet/broadcom/tg3.c +++ b/drivers/net/ethernet/broadcom/tg3.c @@ -8733,14 +8733,15 @@ static void tg3_free_consistent(struct tg3 *tp) tg3_mem_rx_release(tp); tg3_mem_tx_release(tp); - /* Protect tg3_get_stats64() from reading freed tp->hw_stats. */ - tg3_full_lock(tp, 0); + /* tp->hw_stats can be referenced safely: + * 1. under rtnl_lock + * 2. or under tp->lock if TG3_FLAG_INIT_COMPLETE is set. + */ if (tp->hw_stats) { dma_free_coherent(&tp->pdev->dev, sizeof(struct tg3_hw_stats), tp->hw_stats, tp->stats_mapping); tp->hw_stats = NULL; } - tg3_full_unlock(tp); } /* @@ -14178,7 +14179,7 @@ static void tg3_get_stats64(struct net_device *dev, struct tg3 *tp = netdev_priv(dev); spin_lock_bh(&tp->lock); - if (!tp->hw_stats) { + if (!tp->hw_stats || !tg3_flag(tp, INIT_COMPLETE)) { *stats = tp->net_stats_prev; spin_unlock_bh(&tp->lock); return;